Nearly 8 million individuals in the United States currently use smokeless tobacco (ST). ST is known to increase the risk for cancer of the mouth and gum, larynx, and salivary gland. Since two-thirds of current ST users report the desire to quit, a need for effective interventions exists. However, pharmacologic and behavior interventions need to be developed as no pharmacotherapies have been shown to significantly increase long-term (> 6 months) abstinence rates in ST users. Nicotine lozenges are the newest form of nicotine replacement therapy (NRT). The nicotine lozenge is placed in the mouth and not chewed, allowing for a consistent release and absorption of nicotine through the oral mucosa. The nicotine lozenge has demonstrated efficacy for increasing smoking abstinence rates in cigarette smokers but has not been evaluated in the treatment of ST users in a randomized, placebo-controlled clinical trial. Our long-term objective is to develop and test effective pharmacotherapies that can be used clinically to increase tobacco abstinence rates among ST users. The objective of the current proposal is to evaluate the efficacy of the 4-mg nicotine lozenge provided for 3 months for increasing tobacco abstinence rates in individuals reporting ST as their primary tobacco product. The central hypothesis of this application is that nicotine lozenges are efficacious for increasing the long-term (> 6 months) tobacco abstinence rates among ST users. The work will be completed in the setting of a multicenter, randomized, blinded, placebo-controlled clinical trial. We will conduct the work in two sites (Mayo Clinic in Rochester, MN & Oregon Research Institute in Eugene, OR) with a proven track record of ST user recruitment. The primary aim of this application is: 1) To evaluate the efficacy of 12 weeks of 4-mg nicotine lozenges for increasing the prolonged and point prevalent all tobacco abstinence rates at 6 and 12 months compared to placebo lozenges in ST users. The primary hypothesis to be tested is: 12 weeks of 4-mg nicotine lozenges will increase the prolonged and point prevalent all tobacco abstinence rates at 6 and 12 months compared to placebo lozenges in ST users. Relevance: Smokeless tobacco use causes dental disease and cancer of the mouth and throat. No drug therapies have been shown to be effective for helping smokeless tobacco users quit for good. The purpose of this study is to test drugs that can be used to help smokeless tobacco users quit for good. [unreadable] [unreadable] [unreadable]